I have xmr-stak and i was able to get an impressive hashrate from it, but it seemed to be hurting my gpu eth mining, and running my cpu full blast for a very meager profit didnt make sense, so i nixed it. Any suggestions?
Well, assuming CPU power was the bottleneck, you could just set the CPU mining process to use fewer threads or set it to run at a lower priority than your GPU mining software.
As you mentioned, however, mining with your CPU isn't going to near the revenue produced by the GPUs on your rig.
Do note that you can mine Monero with your GPUs, as an alternative to Ethereum. Check for yourself if this would be more profitable.